1. Field of the Invention
The present invention relates to an embroidery pattern data processor that computes needle locations for sewing each of the sections dividing an embroidery based on section data for designating the locations of the vertexes of the polygonal sections dividing a closed area of a given shape, where the embroidery is defined and surrounded by an outline.
2. Related art
An embroidery pattern data processor of this kind has been disclosed in U.S. Pat. No. 4,849,902.
The conventional technique of processing such data has included the steps of displaying a drawing of embroidery filmed by a television camera or the like on a CRT display unit, storing an outline defining the embroidery in a memory by designating points on the outline with a light pen with the displayed image of the embroidery for reference, drawing dividing lines inside the closed area in any order for dividing the closed area into a plurality of polygonal sections, hence successively defining sections having the designated points as their vertexes, and storing the location data for the vertexes as section data. Then, as well known in the art, the data for needle locations is computed based on section data successively read out and predetermined stitch density data. Embroidery is formed on a cloth by moving the needle and the cloth by relative displacement based on the obtained data for needle locations.
As explained above, the actual embroidering is carried out in accordance with the order in which the section data previously stored in the memory are read out. Therefore, if only section data is stored in the memory, cross threads may occur depending on the order in which the section data are stored. In such cases, it is necessary for the operator to remove all the cross threads after embroidering in order to enhance the esthetic value of the embroidery. Removing cross threads is tedious and labor intensive.
When a plurality of separate closed areas in one embroidery pattern are continuously embroidered without thread-cutting, a starting point and an ending point of each closed area must be properly designated. Otherwise, a cross thread stretching from the ending point of one closed area to the starting point of the next closed area may be sewn in the embroidery of one of the closed areas. Removal of such a cross thread is extremely difficult.
Previously, in order to prevent cross threads from occurring, the operator would designate a starting point and an ending point and anticipate the sewing order in which cross threads do not occur before the step where the operator divides a closed area into a plurality of sections for embroidering the closed area surrounded by a given outline. The operator also prepared section data in accordance with the sewing order. If one section is located separately from the previous section for which the section data has just been prepared, the data for needle locations to form running stitches which run within the sections to the top therethrough are successively prepared. At this point, the section data for sewing the section from the end of the running stitch to the start thereof is prepared. For instance, to form T-shaped embroidery with a point Pl as the starting point and a point P9 as the ending point as shown in FIG. 9, points P1 and P2 are first designated. Second, points P3 and P4 are designated so that a line segment P3P4 divides the closed area S. Thirdly, the point P4, a point q, and a point P5 are designated for forming running stitches running from the point P4 to the point P5. The location data for the points P4, q, and P5 are stored as the running stitch data. Next, the section data for a section B2 is prepared by designating the point P5, a point P6, the point P3, and the point P4. Likewise, the point P4, a point P7, a point P8, and a point P9 are designated in preparation for the section data for a section B3.
As well known to those skilled in the art, the first two points Pl, P2 are on the side where the embroidering starts while the latter two points P8, P9 are on the side where the embroidering ends. In other words, the running stitches process from the point P4 to the point P5, whereas the embroidering of the section B2 is carried out in the opposite direction from the point P5 to the point P4. This prevents cross threads from occurring.
As is clear from the foregoing explanation, the conventional apparatus necessitates the preparation of section data and running stitch data by the operator, which preparation is difficult, is time-consuming, and requires skill.